1. Field
The present embodiments relate to a backlight unit and driving method thereof, and a liquid crystal display device having the backlight unit.
2. Related Art
A liquid crystal display (LCD) device has been used in various applications including notebook computers, personal computers (PC), television monitors, and the like. The LCD device has a small volume, is lightweight and has low power consumption characteristics.
The LCD device is a light receiving device that displays an image by adjusting the amount of light incident from an outside light source. Accordingly, the LCD device needs a backlight unit for illuminating light into an LCD panel.
Generally, backlight units are classified into edge type backlight units and direct type backlight units depending on the arrangement of the light source. The edge type backlight unit has a light source arranged on a side of the LCD device and a light guide plate disposed on a rear of the LCD panel. The light guide plate guides the light emitted from the side toward a front surface of the LCD panel. The direct type backlight unit has a plurality of light sources arranged on the rear of the LCD panel. The light emitted from the plurality of light sources is directly illuminated into the LCD panel.
The light sources used for those backlight units include lamps, for example, an electro luminescence (EL), a cold cathode fluorescent lamp (CCFL), and a hot cathode fluorescent lamp (HCFL), and a light emitting diode (LED).
Typically, the lamps include a glass tube, an inert gas filled in the glass tube, for example, Ar, Ne, or the like, a phosphor coated on an inner wall of the glass tube, and an electrode that supplies a voltage to an inside or an outside of the glass tube.
In the above lamps, when a voltage is applied to the electrode, electrons emit from the electrode, collide with the inert gas to emit UV rays, and the UV rays collide with the phosphor coated on the inner wall of the glass tube to emit visible rays.
In a dark state, which does not have an external illumination, the inert gases colliding with the electrons in the lamp are excited (or ionized) with a time delay.
The related art LCD device has a problem that the quality of an image displayed in an initial stage is deteriorated due to the delay in the excitation time of the inert gases when the lamp is driven in a dark state, especially in a low temperature state.
SUMMARY The present embodiments may obviate one or more problems due to limitations and disadvantages of the related art. For example, in one embodiment, a backlight unit and driving method thereof can stably drive a light source by providing a minimal illuminance.
In one embodiment, a backlight unit includes a lamp and an inverter that supplies a driving voltage to the lamp. An illuminance correction system senses a surrounding luminance of the lamp to illuminate a predetermined amount of light.
In one embodiment, a liquid crystal display device includes an illuminance correction system that senses a surrounding illuminance of a lamp to illuminate a predetermined amount of light. A liquid crystal display panel displays an image using the light emitted from the lamp.
In another embodiment, a method of driving a backlight unit includes sensing a surrounding illuminance of a lamp at a light sensor; comparing the surrounding illuminance sensed by the light sensor with a preset reference illuminance (1 lx); generating On/Off control signal of a light emitting device according to a result of the comparing; and driving or stopping the light emitting device according to the On/Off control signal.
It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.